Metathesis reaction such as ring-opening metathesis polymerization or ring-closing metathesis reaction of an olefin compound, cross metathesis reaction of an acyclic olefin, or metathesis polymerization of an acyclic diene is an industrially advantageous reaction. The metathesis reaction is carried out in the presence of a catalyst. As the catalyst used, a catalyst system comprising a transition metal compound such as tungsten, molybdenum, or titanium and an organometal reducing agent such as an organoaluminum compound or organotin compound in combination has been conventionally known. However, in the catalyst system, a plurality of catalytically active species is produced, and the produced catalytically active species are unstable and soon become deactivated. Therefore, it is difficult to control the metathesis reaction.
In recent years, it has been reported that a transition metal-carbene complex with a carbene compound being bonded to a transition metal exhibits high catalytic activity and can control various metathesis reactions at a high degree. For example, publication of European Patent application No. 218138 and “Metathesis Polymerization of Olefins and Polymerization of Alkynes”, 1996, p. 1, Kluwer Academic Publisher, Boston describe that a carbene complex of molybdenum or tungsten having bulky alkoxide and imide ligands is a highly active metathesis reaction catalyst and that a cyclic olefin polymer having comparatively high stereospecificity can be obtained by ring-opening metathesis polymerization of cyclic oleifn when this complex is used.
Nowadays, a ruthenium complex compound with a carbene compound being bonded to ruthenium (hereinafter may be referred to as “ruthenium-carbene complex”) which is hardly affected by water or an alcohol has attracted attention. For example, as a highly active metathesis reaction catalyst for an olefin compound, WO 96/04289 describes a ruthenium-carbene complex having a phosphine as a ligand. Japanese Patent Application Laid-open No. 10-195182 describes a process which comprises polymerizing a cyclic olefin by ring-opening metathesis polymerization in the presence of a ruthenium-carbene complex compound having a phosphine as a ligand, followed by hydrogenating olefinic double bonds in the ring-opened polymer without addition of a hydrogenation catalyst.
WO 99/51344 and WO 00/15339 describe a ruthenium-carbene complex having a substituted imidazolin-2-ylidene or substituted imidazolidin-2-ylidene, which is a heterocyclic carbene compound comprising a five-membered ring structure, as a ligand instead of a phosphine. The specifications relate that this catalyst exhibits extremely high catalytic activity and present an example of the reaction using a ruthenium-carbene complex having substituted imidazolin-2-ylidenes with different substituents at the 1-position and 3-position as a ligand. However, since ruthenium is a rare and expensive metal, further activation of a ruthenium-carbene complex has been demanded.
A ring-opened polymer of a cyclic olefin, in particular, a polymer of norbornene monomers and a hydrogenated product of the polymer are amorphous polymers. Therefore, the polymers have been conventionally known to have excellent transparency, heat resistance, low birefringence, formability, and the like, and are suitable as a material for optical disks and optical lenses. Further, the ring-opened polymer and the hydrogenated product have been applied to products other than optical goods, due to their other excellent properties such as low dielecticity and chemical resistance. In particular, a hydrogenated product of a ring-opened polymer of dicyclopentadiene (DCP) which is the most common norbornene monomer exhibits excellent mechanical strength and has been expected to be widely applied to products other than optical goods.
However, the hydrogenated product of ring-opened DCP polymer has a glass transition temperature (Tg) of 97° C. or less (Polymer Journal, 1995, vol. 27, p. 1167) and there is a problem about heat resistance of the product. For example, such a product cannot be used for medical appliances requiring steam sterilization resistance or electric components of which the inside is heated to a high temperature. The polymer must have a Tg of 100° C. or more for such medical appliances and electric components.
Specifically, a hydrogenated product of ring-opened DCP polymer having a Tg of 100° C. or more cannot be obtained, not only in the case of using a conventional catalyst system comprising a transition metal compound and an organometal reducing agent in combination, but also in the case of using a recently proposed molybdenum-carbene complex compound, tungsten-carbene complex compound, or ruthenium-carbene complex compound.
The present invention has been achieved in view of such a situation. An object of the present invention is to provide a novel and highly catalytically active ruthenium complex compound and a process for producing the same, a process for producing a ring-opened cyclic olefin polymer and a hydrogenated product of the same using the ruthenium complex compound as a metathesis reaction catalyst or a hydrogenation catalyst, and a hydrogenated product of ring-opened dicyclopentadiene polymer exhibiting excellent heat resistance.